Subsea installations are subjected to the build-up of scaling, especially calcium-based scaling. In certain situations, such scaling may give operational delays. It may lead to overstraining of, for example, valve stems and a frequent need for mechanical cleaning of seal surfaces. The problems created by scaling are sought to be solved by affected components being treated with an acid solution, the acid reacting with the scaling and dissolving it. Often, a weak citric acid is used which is formed from powder or granulate and water, which is then filled into containers that are transported to the treatment site where a diver or an ROV (Remotely Operated Vehicle) carries out the treatment of the installation. The treatment takes place by the acid solution being sprayed slowly at the detail, which is to be treated, trying to keep the loss of acid solution into the surroundings as small as possible. Loss is still inevitable, and this often results in more acid solution having to be picked up at the surface, which is time-consuming and costly.